Southern Santa Fe Province in Argentina has many shallow lakes embedded in a landscape where 70%of the area is used as grazing pastures and agricultural fields. These lakes are key lowland habitats for Andean Flamingos Phoenicoparrus andinus, especially during winter when some of the lakes in their primary habitats in the Andes of Argentina, Bolivia, Chile and Peru freeze. This year we carried out summer and winter surveys(January and August 2010, respectively) throughout the area in order to determine seasonal differences in flamingo abundance. We recorded a total of 13,756 Chilean Flamingos Phoenicopterus chilensis in summer and 13,333 in winter. We recorded 19 Andean Flamingos in summer and 2,587 in winter. There were also 385 flamingos that we were unable to identify to species in summer and 1,491 in winter. Finally, we recorded two Puna Flamingos Phoenicoparrus jamesi in winter at Melincué, constituting the first observation of this species at this site, usually considered outside the distribution range for the species. The survey data show that Andean Flamingos were primarily present in this area during winter. These observations highlight the need to continue to survey and monitor these important habitats in both winter and summer over several years, and to broaden the survey area to cover more wetlands that may be providing winter habitat for Andean Flamingos.